Coolants have the effects of cooling, lubricating and removing chips, and are used as cutting fluids or grinding fluids in cutting and grinding processes. Coolants work as follows: the cooling effect absorbs friction heat and heat of metals generated between a workpiece and a tool or between a tool and chips, and cools the workpiece, tool, and other components of a machine tool; the lubricating effect reduces friction between a workpiece and a tool or a tool and chips by coolant flowing between the workpiece and the tool or the tool and the chips, thereby preventing generation of a built-up edge and welding of chips onto a tool cutting face; and the chip removing effect is achieved by coolant jetted with a given pressure and a given flow rate removing chips from a processing point and controlling the direction in which chips are removed, forcing chips to drop off the top surface of a workpiece, or forcing chips in a trough to flow in a specified direction. While coolant may be jetted by any pressure such as a pressure as high as 7 MPa or higher.
Coolants can be jetted to a processing point in various ways. The pressure of coolant, the flow rate of coolant, the temperature of coolant, jet duration, an jet position, and other parameters are determined according to a process mode, and a suitable coolant supply apparatus as a coolant jet is used. Patent Literature 1 discloses a coolant pumping apparatus used for a coolant supply apparatus and Patent Literature 2 discloses a coolant supply apparatus.
Patent Literature 1 discloses a coolant pumping apparatus including an inverter device and discloses that the rotation speed of the electric motor is made variable by an inverter control to supply required amounts of coolant to a plurality of processing positions, thereby minimizing wasteful jet of coolant to reduce power loss.
Patent Literature 2 discloses the use of an ON timer and an OFF timer that turn on and off at least one on-off valve provided for each branch passage to control the amounts of a coolant supplied to a plurality of washing positions.
PLT 1: Japanese Unexamined Patent Publication (Kokai) No. 07-127565
PLT 2: Japanese Unexamined Patent Publication (Kokai) No. 2007-30109